Patellar tendonitis develops when the stress placed on the tendon exceeds its ability to handle the load. Repetitive activities such as jumping, running, and squatting are the most common contributors.
External factors like improper footwear, training errors, and hard surfaces can increase strain on the knee. A rapid increase in training intensity or duration—often described as doing “too much, too fast”—is a major cause of this condition.
Internal factors also play a role. These include reduced flexibility, joint laxity, and alignment issues in the lower body. Structural variations such as flat feet, leg length differences, or abnormal tracking of the kneecap can lead to uneven stress on the tendon.
Muscle imbalances, especially between the quadriceps and surrounding muscles, can further increase strain. Over time, repeated microtrauma prevents proper healing, leading to inflammation. In chronic cases, degeneration of the tendon may occur, a condition referred to as tendinosis.